code: def _add_option(self, name, default):
      if name in self._values:
          raise RuntimeError(f"Config option {name} already defined")
      self._values[name] = default
  
file_path: flax/flax/configurations.py
imports: import os
  from contextlib import contextmanager
  from typing import Any, Generic, NoReturn, TypeVar, overload
label_desc: Use image node_id 2 for calling the Config obj's underlying member method code with example usage: obj._add_option(name, default) without return types